The present invention relates to the mounting of electrical and electronic equipment, and more particularly to mounting and thermal management of avionic systems.
Avionic systems are mounted within an aircraft electronics bay to provide reliability and serviceability. Significant considerations of avionic system mounting are the thermal management and structural support thereof.
Avionic systems commonly include a multitude of printed wiring board assemblies (PWBs) mounted within electronic equipment racks. The construction of the racks typically includes integrated thermal management schemes such as edge cooling. Edge-cooling allows the heat produced in an electronic circuit to be rejected by conduction through the PWB surface and communicated to the PWB edges. The PWB edges are mounted in the rack and are cooled by flowing liquid or air adjacent thereto. Depending on the required heat dissipation level of the electronic circuit, additional cooling conductors such as an aluminum core, a flow-through module, and high conductivity graphite cores may be located within the PWB. Although providing effective thermal management, incorporating additional cooling conductors within the PWBs may significantly increase the manufacturing expense and weight of each PWB.
To minimize the weight thereof, PWBs are manufactured as relatively thin structures. However, the thinness of the PWBs results in a relatively flexible structure which may deflect in response to the vibratory inputs of typical aircraft operating environments. To minimize excessive deflection of the PWB assembly, structural stiffeners such as metallic bars are commonly mounted to the PWB surface. Although effective at adding stiffness to the PWB, conventional structural stiffeners are of a thin construction to also minimize weight. This thinness results in minimal thermal transfer. However, increasing the size of the structural stiffener to provide thermal transfer through conduction would result in an undesirable weight increase.
Accordingly, it is desirable to provide an electronic equipment rack system which increases the thermal management and structural support of a printed wiring board in an inexpensive and lightweight package.